Landfill Sites & Disposal of Nuclear Waste

Question 1

What are the Environmental Consequences of Landfill?

Answer 1

• During the waste tipping operation, there are issues of noise, dust, smells and vermin infestations.
• Biodegradable waste starts to compose, the landfill undergoes settling and subsidence. This is a major problem because it results in cracks and fissures opening up allowing rainwater to infiltrate into the waste.
• As rainwater percolates down through the waste, it dissolves soluble chemicals and collects microbial contaminants producing a liquid we call leachate.

Question 2

How Does Rock Type Affect Landfill Location?

Answer 2

Fine grained, impermeable rocks such as clays are most suitable for landfill sites and it is best if they have a thick, uniform, flat lying beds. Porous and permeable rocks such as limestone and sandstone allow the flow of leachate. Limestone may be dissolved by acidic leachate leading to the formation of solution cavities, which will destabilise the site. Cementation acts as a barrier to leachate flow, but physical and chemical weathering can increase the permeability making leakage more likely. Crystalline igneous and metamorphic rocks may be suitable, but can be affected by jointing and foliation.

Question 3

How Do Geological Structures and the Attitude of Strata Affect Landfill Location?

Answer 3

Faults increase the permeability f rocks and provide escape routes for leachate.
Joints in rocks such as limestone also allow downward leakage of leachate. Tilted or folded beds allow down-dip and lateral movement of leachate, which can migrate some distance away from the landfill site through permeable beds.

Question 4

How Does Groundwater Affect Landfill Location?

Answer 4

If the water table is high then there is less distance for the leachate to travel to reach the underlying groundwater.

Question 5

How Do You Prevent The Leakage of Leachate?

Answer 5

1) Grouting the surrounding rocks - holes are drilled and cement is injected into pore spaces to reduce permeability and close fissures, joints, bedding planes etc.
2) Laying an impermeable clay or geomembrane (plastic lining).
3) Draining and collecting the leachate, which can then be treated or safely stored.

Question 6

What Criteria Must The Safe Disposal of Radioactive Waste Include?

Answer 6

• Isolation for at least 250,000 years.
• Secure from accidental or deliberate entry.
• Safe from natural disasters such as floods, hurricanes and earthquakes.
• No chance of leakage into the surrounding environment.